supercharged H22

[toycar]

I run an off the shelf 264 intake and 272 exhaust cam on my street driven dsm, then degreed from there. Since the intake charge has been compressed, a shorter valve duration maintains better intake pressures.

The compressed air and fuel expand and need more time to escape the cylinder, so a longer exhaust duration is beneficial.

A custom cam would really be ideal.

[deevergote]

That's true. That's the beauty of DOHC!
Still, with that cam profile, adjusting N/A cams to reduce overlap will probably result in decreased performance, as the profiles were made to utilize that overlap.
I'm going beyond my area of expertise here, though.

[cincy90h22]

Yes I know that. But with adjustable cam gears you can adjust for that. How much overlap does it have, and how much can I get rid of, im not sure yet. Or would it be easier to get another set of cams.. thats another thing im going address. It may be benificial to get turbo cams anyway and swap them during tuning and see what happens.

[toycar]

N/A cams provide a significant amount of valve overlap, which is useful in N/A applications. With forced induction, you're essentially blowing that fresh charge out the exhaust valves during that overlap period. You'd probably see much better results with a turbo cam profile.

Yup, and as a result cylinder pressure is suffering.


His fuel issues will be irrelevant if he can either run race gas, e85 or a meth kit.


Any of the 3 will put him into a position that high comp + boost is very safe. I personally would run a meth kit, because it not only bumps octane but lowers charge temps. Something I am sure he is already fighting with.


Also, I would consider an air to water intercooler to keep it sneaky under the hood.






All of these suggestions are only that, suggestions. The car is baller and looks great from square one. Nice fab work, nice work in general. I probably wouldn't mess with it much at all from where it is now.


Especially if you are trying to promote business with the car. Reliable sells a lot more service than HP from my experience. Its every car guys worst fear to dump 10k into a car just to have it explode on them.


Reliable vs fast in the point of sale industry, and reliable wins 99/100 times.

[deevergote]

N/A cams provide a significant amount of valve overlap, which is useful in N/A applications. With forced induction, you're essentially blowing that fresh charge out the exhaust valves during that overlap period. You'd probably see much better results with a turbo cam profile.

[cincy90h22]

I honestly dont remeber what the iat were. Not bad considering it was pulling hot air off the header, before I made the air intake duct to the charger.

My cams are skunk2 stage 2 n/a cams. I like them, but am not opposed to changing them. I saw a study where they made good improvement over stock cams in a forced induction application. Of course they shift the powerband higher, which can be good for traction. Some headwork is in store for it going back together though.

[toycar]

Meth kit will raise octane levels to a point that detonation isn't really an issue. It will also cool charge temps pretty drastically.


What are your iat's?

I personally would just go 11.5:1 on stock bore, get some cam work done and you'll break 300whp no problemo.

The supercharger flows over 1000cfm. I would probably get the pulleys dialed I to reach peak boost at 3-4000 rpm. You are not going to surge that compressor with this motor.

It just won't happen. You could run a larger charge pipe to keep pressure down while increasing flow. The compressor flows so much air that the pressure actually slows down airflow. It's the pressure that provides resistance in the compressor housing. Larger pipes, smaller pulley, same pressure but more flow.

The psi of your charge has a lot to do with raised temps associated with it as well. Less pressure, more flow.


There's lots you could do really. Thing is, I don't think you're gonna be happy with much more power on the street.


I would def focus on moving the powerband around with cam work, and keeping things reliable. You are probably only getting 70-80% of your already made power to the ground. Making more power will equate to getting more power to the ground, but making more power is not the only way to go faster.


I do think a better header would help, but you've got way more bang for the buck available in cam work.

[cincy90h22]

Correct.. It basically drives like a stock motor. Now my smaller pulley is more effective. Lol.
3k 2psi
4k 4psi
5k 6psi
6k 8psi
7k 10psi

Somewhat like that. Its so freakin smooth, the higher the rpm though the faster it revs.

[deevergote]

That's true. Roots is more of a direct delivery. Not peak power instantly, but it puts the power down faster than a turbo.

So essentially, if you drive between 2k and 3k RPM (how I drive when I'm just taking it easy), you're really not putting out much boost at all...

[cincy90h22]

That is the beauty of the supercharger, its simple to tune, it hits the same fuel tables evertime.

The power gained from the charger isnt 'instant'. For example: my first dyno looked like
Rpms boost
2k. 0 psi
3k. .5
4k. 1
5k. 1.75
6k. 2.5
7k. 3.4
8k. 4.6

Granted I was not spinning the charger in its efficiency range. But its not like you have max psi from the start. A roots type may be different idk.

[deevergote]

He's running a top mount intercooler already. It's a centrifugal supercharger, so it's essentially the compressor housing of a turbo driven by the crank. Everything from the compressor outlet on can be treated much like a turbo.


If I may ask, what's your reason for wanting such high compression? It's definitely doable, but are the gains really going to be that significant? It seems that high compression is going to drastically reduce your margin of error when tuning (at least a supercharger's output is more reliable, more linear, than a turbo... which can surge unexpectedly.) You essentially have an impressive N/A engine with a supercharger bolted to it!

Seeing what you've done with what, under 5psi? I would imagine 12psi, higher compression, and a good tune should plop you in the 400ish area, yeah. That much power might actually be very difficult to use, given the low-end supplied by the supercharger. At least a turbo doesn't overpower the front wheels right away... it has to spool. Your setup will be providing power almost instantly.

[cincy90h22]

I have an intercooler already. Its essentially a top mount, not a front mount, for a more sleeper effect.

[gloryaccordy]

I would keep it as is and maybe just work on bolstering the system's reliability

Would it be possible to install an intercooler?

[cincy90h22]

Realisticly.. an off the shelf 11.5:1 piston would be suffecient. Otherwise im looking at a steeper price and more machine work to fit the custom 12/12.5:1 pistons that are a minimum. .5mm overbore, and going to require higher octane fuel. E85 isnt easily acessable in my area. I do plan on driving this car frequently, and at the higher cost of fuel or additives, and overall probably too much power for the street, I am contemplating my build plan. @ 12.5:1 and 12psi I would guesstimate 375-400whp?

Any input anyone?

[cincy90h22]

You are vey right toycar..

I am not making a dyno queen, or a track car. It will probably never see a quarter mile. Too much power for the street is pointless, I do want to drive it on nice days and such. I dont have a power goal in mind, whatever I get im fine with. But I wanna do something different, obviously with the sc, but high compession as well.

I work at my fathers repair shop, and im adding my know-how to the business and branching off into engine building, modifying and tuning etc. This car, is basically advertising my skills as a fabricator, since I have done everything myself except a few machine work items, and tuning (for now). We dont have but one or two good tuner shops in 100 mile radius of me.